UCL News

Services

Get updates from UCL News

Psychogenic diseases linked to abnormal brain activity

25 February 2013

Individuals with psychogenic disease (i.e. physical illness stemming from emotional or mental stresses) have
brains that function differently to people with organic diseases, according to new research from UCL and the University of Cambridge.

Psychogenic
diseases, formerly known as ‘hysterical’ illnesses, may look very similar to genetic diseases of the nervous system or to illnesses caused by damage to the nerves,
brain or muscles. They can result in many severe
symptoms, such as painful cramps or paralysis.

However, unlike organic diseases, psychogenic diseases do not have any apparent
physical cause, making them difficult to diagnose and even more difficult to
treat.

This
study looked at people with either psychogenic or organic dystonia (a movement disorder in which sustained muscle contractions cause twisting and repetitive movements or abnormal postures), as well as
healthy people with no dystonia.

Both types of dystonia caused painful and
disabling muscle contractions affecting the leg.

Understanding these disorders, diagnosing them early and finding the right treatment are all clearly very important. We are hopeful that these results might help doctors and patients understand the mechanism leading to this disorder, and guide better treatments.

Dr Anette Schrag, UCL Institute of Neurology

The organic patient group had
a gene mutation (the DYT1 gene) that caused their dystonia. The psychogenic
patients had the symptoms of dystonia but did not have any physical explanation
for the disease, even after extensive investigations.

The
scientists performed PET brain scans on the volunteers at UCL to measure the
blood flow and brain activity of both dystonia groups and the healthy volunteers.
The participants were scanned with three different foot positions: resting, moving
their foot, and holding their leg in a dystonic position. The electrical
activity of the leg muscles was measured at the same time to determine which
muscles were engaged during the scans.

The
researchers found that the brain function of individuals with the psychogenic
illness was very different to the brain function of individuals with the organic (genetic) disease.

First author Dr
Anette Schrag, from the UCL Institute of Neurology, says: “Finding abnormalities of brain function that
are very different from those in the organic form of dystonia opens up a way
for researchers to learn how psychological factors can, by changing brain
function, lead to physical problems.”

Dr James
Rowe, University of Cambridge, added: “What struck me was just how very different the abnormal brain
function was in patients with the genetic and the psychogenic dystonia. Even
more striking was that the differences were there all the time, whether the
patients were resting or trying to move.”

In addition,
the researchers found that one part of the brain (the prefrontal cortex) previously associated with
psychogenic disease is an unreliable indicator. Abnormal activity in this region is not unique to psychogenic disease and the same pattern of activity was also observed in patients with organic dystonia when they tried to
move their feet.

Dr
Arpan Mehta, from the University of Cambridge, says: "It is interesting
that, despite the differences, both types of patient had one thing in common -
a problem at the front of the brain. This area controls attention to our
movements and although the abnormality is not unique to psychogenic dystonia,
it is part of the problem."

This
type of illness is very common, as Dr Schrag explains: “One in six patients that see a
neurologist has a psychogenic illness. They are as ill as someone with organic
disease, but with a different cause and different treatment needs. Understanding
these disorders, diagnosing them early and finding the right treatment are all
clearly very important. We are hopeful that these results might help doctors
and patients understand the mechanism leading to this disorder, and guide
better treatments.”